Need some help, car won't idle.

[dangerous]

Hey folks! I have a little problem here, I’m wondering if you could help me out? The combined knowledge and experience of this forum never ceases to amaze me!

Here’s the story. I’m providing a lot of details as they may be relevant to someone out there. I apologize for the excess, just trying to be thorough and felt that too much info is better than not enough. For those who want to cut to the chase, skip ahead to the last paragraph.

My car is an 85.5 944 N/A. The maintenance had been procrastinated a bit here and there until last summer. My “to do” list included replacing the cam belt, balancing shaft belt, the 4 applicable rollers, front-end seals. I also pulled the head for a valve job and replace the valve guides (and stem seals). Also replaced fuel filter, air filter, oil filter, dist cap, rotor, thermostat, thermo switch, all applicable gaskets and had some welding done on my exhaust manifold. While in there I inspected the cylinder walls and cleaned up the piston heads. Took a bunch of photos of most of the process, which I’ll send to Clark’s Garage (and anyone else who may be interested) in case he wants to use them.

About a month before the project, my car developed some vibrations and I posted a prompt here and received suggestions relating to the balance shaft belt.

One day about a week before the project started the started running real bad. I was only a couple of blocks from home so I managed to limp back to the nest but it was bad. It ran very rough and felt like a misfire. The car wouldn’t idle, would stall unless I kept the RPM’s up…again reminiscent of a misfire. I’ve been driving this car for 10 years now and been through my share of troubles/repairs etc but I can’t really recall this car ever misfiring for any reason. I’ve experience plenty of misfires on other engines though. I suspected that the neglected maintenance on the ignition system was a likely culprit so I decided to park the car and begin the project as planned. If the problem returned I would be able to rule out a bunch of newly replaced parts all at once.

When I opened the belt covers I did in fact find that my balance shaft belt had snapped and was wedged around the lower balance shaft gear. First mystery solved. I removed the belts, pulled the head, had the valve job done when there was a hiatus of 4 months due to some professional obligations. I got back to work on the car recently and managed to get puzzle back together without any extra pieces. Today I started the engine for the first time. It ran rough for a few seconds then began to smooth out. I realized that the prolonged sit probably wasn’t the best for the engine but I did remember to add a little oil to the cylinders before the first fire up and made sure the oil level was up to par before the first start. The cam and lifters tapped for a few seconds then the oil reached them and they were happy. I stopped the engine, checked and added a little more oil to the pan then fired it up again. After a few moments the engine was running smooth and ….well….I don’t really know how to describe it other than it felt light and very responsive. Not dogged and tired like it did before the project.

THE PROBLEM: It wouldn’t idle. When I release the gas pedal, it just dies. Doesn’t sputter, just cuts out. Now when I reconnected the throttle cable, I noticed that it had slack. I paused in confusion, as I don’t ever recall the cable having any slack in it. I played around with it a bit but it seemed to be connected securely. I may have screwed up the reinstallation but it doesn’t seem that difficult…I mean after everything else I just did, the throttle cable seemed about as complicated as oiling a bicycle chain! But nevertheless, I’m standing here scratching my head. The car doesn’t idle rough like it’s misfiring, it just seems like the slack in the throttle cable allows the throttle to close all the way and cut off the fuel. I didn’t mess with the screw the stops the throttle lever though. The only thing I did was wipe off the oil crud that was obviously sucked into the throttle body from my leaky balance shaft seals. I noticed the cable tension adjuster in the firewall, which is backed out almost all of the way, but I have never touched that either. I did notice what appears to be a darker area of throttle cable where it enters the sheathing, which may indicate a change in cable length. So I’m wondering if this situation is in anyway related to what initially appeared to be a misfire last summer? Is slack in the throttle cable going to affect the car’s idle? If so, what could be causing the slack? Is it possible that an idle adjustment is needed in light of the recently replaced parts?

Any ideas?

[AFJuvat]

By what you have described, it sounds like you have a combination of one or more of the following:

Throttle cable too slack - the adjustment is on the firewall side of the cable.

When you took everything apart, you cleaned up the throttle body and associated parts (I'm guessing, but most people see how dirty they are and clean them) If you've cleaned it, chances are the throttle valve and air bypass are slightly out of adjustment.

Tighten up the cable, You want the cable tight enough to where as the throttle just starts to move, you hear the throttle switch click. If the cable is tight and you can't get a click right away, you will need to adjust the butterfly position (the stop screw with the jam nut) or the throttle switch itself.

Once you have that set, let the engine warm up and check your idle. you adjust the idle with the recessed 7 or 8mm bolt that is recessed in the throttle body.

AFJuvat

[dangerous]

AFJuvat

Thanks for your reply! I will try these suggestions tomorrow.

I am wondering about the cable slack problem though. I have no idea where the slack came from. Also I notice the adjustment mechanism on the firewall, it's screwed "out" almost all of the way which appears to be how to tighten it. I'll try screwing it "in" tomorrow though. Is there anything that might cause the cable to strecth? Or any kind of spacer that might have fallen off?

[SoCal Driver]

I thought the stop on the throttle body was to set the idle. The cable was to be a tad slack to allow this. Been running mine like this since 85.

I would add that all of your vacuum hoses need to be tight. Could have had one loosen up. Also your intake tube/boot/duct thing that goes between the AFS and the throttle body.

Check the idle switch setting on the throttle body.

[dangerous]

SoCal Driver

Yeah, that does make sense. If the cable was responsible for maintaining an idle speed then the stop wouldn't have a purpose. My initial intuition that the cable slack was causing the problem was probably wrong.

I was pondering something last night. when I wiped off the sludge in the interior of the throttle body, I must have disturbed something. I still need to check a few things that AFJuvat suggested though, but I was wondering if there was a small hole that allows air to enter on the other side of the butterfly for idling. Kinda like on a carburetor accept that it would be for air instead of fuel. I don't really know, I must confess I am a bit ignorant about the workings of Fuel Injection Sytems. But if there were such a hole on there, perhaps I smeared sludge into it when I wiped the crudd off the inner surface.

I'll be continuing the research as I cannot work on the car until Monday.

SoCal, Thanks for your input. I'll try to improve the cable tension but won't lose sleep over it.

[SoCal Driver]

If you tried to clean the throttle body then you could have something blocking the air bypass that the large adjusting screw regulates. Also the throttle switch should just click as the butterfly closes.

I had to take mine off a few years back and clean the heck out of it because it was sticking. Seems a lot of the crank case blowby builds up at the throttle body.

Don't forget to change the o-ring on the set screw.